I've recently replaced a NE motor to fix a downed quad. After calibrating the drone, I got some weird behavior from two other motors (NW and SW; See the video below).
Symptoms: Basically, the motors arm alright (they seem to have some stick at the beginning), but they cut out at around 40% throttle. The Motors will stop, and the flight controller beeps. when I throttle down, the flight controller beeps again, once. If I throttle-up again, the motors will spin, repeating the process.
Hypothesis 1: It seems like there's a load on the motor, causing an over-amp error (which would make the flight controller cut the power).
According to the research I've been doing, it would make sense since the battery I'm using in the video has suffered a couple worrying prop strikes. (I'm going to retire it pretty soon, but my multimeter says the voltage is okay.) However, I'm having a hard time believing that's the problem, since it's only the two motors that were acting up. I'm more inclined to believe that it's a problem regarding my new, experimental maintenance procedure.
Hypothesis 2: According to a co-worker's suggestion (and backed up by this research), I decided to try brake cleaner to clean out my motors. I sprayed a little in the bells, and spun them with my hands to get some of the dust/dirt out. Since brake cleaner dries out the components, I put 3-in-0ne general purpose oil around the shaft and the bearings. (Note that 3-in-one DOES make an oil specific to electric motors, but I could not find this sold locally.)
I used the brake cleaner + 3-in-one combo on the three motors, but not the new one that I just replaced. This would strengthen the assumption that it's the cause for the two motors acting up.
Hypothesis 3: The last thing I could think is that maybe I've just calibrated poorly. The first forum post that I linked to suggested that a TX could be sending too much input to a motor. Since I'm a rookie pilot who only understands about 80% of the calibration procedure, this could be a cause. (I use Librepilot, and run my quad through the vehicle setup wizards whenever I make a major repair. This has not caused any issues so far, so I'm assuming I'm doing everything correctly on that end.)
Closing thoughts: If you're still reading by this point, I thank you for your time. I'll probably do some more tinkering when I get home from work today, so I'd welcome any input anybody couple provide. Let me know if there's more information I can/should include. I'd love to get flying again.
Looks like it was the battery. I tried a different one and all the motors worked normally. Took it out with that battery in it, and it flew. It was behaving a little strangely toward the bottom of the battery, but I'll have to test it out after a recharge.